Degradation Assembly

Abstract

In one aspect of the invention, a tool has a working portion with a least one impact tip brazed to a carbide extension. The carbide extension has a cavity formed in a base end and is adapted to interlock with a shank assembly of the cutting element assembly. The shank assembly has a locking mechanism adapted to interlock a first end of the shank assembly within the cavity. The locking mechanism has a radially extending catch formed in the first end of the shank assembly. The shank assembly has an outer surface at a second end of the shank assembly adapted to be press-fitted within a recess of a driving mechanism. The outer surface of the shank assembly has a coefficient of thermal expansion of 110 percent or more than a coefficient of thermal expansion of a material of the driving mechanism.

Description

[0001]This application is a continuation of U.S. patent application Ser. No. 12 / 051,586 which is a continuation of U.S. patent application Ser. No. 12 / 021,051 which is a continuation-in-part of U.S. patent application Ser. No. 12 / 021,019 which was a continuation in-part of U.S. patent application Ser. No. 11 / 971,965 which is a continuation of U.S. patent application Ser. No. 11 / 947,644, which was a continuation-in-part of U.S. patent application Ser. No. 11 / 844,586. U.S. patent application Ser. No. 11 / 844,586 is a continuation in-part of U.S. patent application Ser. No. 11 / 829,761. U.S. patent application Ser. No. 11 / 829,761 is a continuation in-part of U.S. patent application Ser. No. 11 / 773,271. U.S. patent application Ser. No. 11 / 773,271 is a continuation in-part of U.S. patent application Ser. No. 11 / 766,903. U.S. patent application Ser. No. 11 / 766,903 is a continuation of U.S. patent application Ser. No. 11 / 766,865. U.S. patent application Ser. No. 11 / 766,865 is a continuation ...

AI Technical Summary

Benefits of technology

The invention is a degradation assembly for use in drill bits and mining picks. It includes a working portion with an impact tip brazed to a carbide extension. The carbide extension has a cavity that interlocks with a shank assembly. The shank assembly has a locking mechanism that interlocks with the cavity. The shank assembly is press-fitted into a recess of a driving mechanism. The assembly has a coefficient of thermal expansion that matches or exceeds that of the driving mechanism. The invention also includes an insert that may be a ring, snap ring, split ring, or flexible ring, or a combination of these. The locking mechanism is mechanically connected to the outer surface of the shank assembly and applies tension along its length. The tip may be made of a superhard material bonded to a cemented metal carbide substrate at a non-planar interface. The assembly may be used in drill bits, shear bits, percussion bits, roller cone bits, mining picks, trenching picks, asphalt picks, excavating picks, or combinations thereof.

Problems solved by technology

Such cutting elements are often subjected to intense forces, torques, vibration, high temperatures and temperature differentials during operation.

As a result, stresses within the structure may begin to form.

Drag bits for example may exhibit stresses aggravated by drilling anomalies during well boring operations such as bit whirl or bounce often resulting in spalling, delamination or fracture of the superhard abrasive layer or the substrate thereby reducing or eliminating the cutting elements efficacy and decreasing overall drill bit wear life.

Damage typically found in drag bits may be a result of shear failures, although non-shear modes of failure are not uncommon The interface between the super hard material layer and substrate is particularly susceptible to non-shear failure modes due to inherent residual stresses.

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